Liquid coating apparatus

Abstract

A liquid coating apparatus includes a liquid chamber, a diaphragm deformable to change a volume of the liquid chamber, a piezoelectric element that deforms the diaphragm in a thickness direction, a pressurized casing bottom-wall portion between the piezoelectric element and the diaphragm to support the piezoelectric element from a diaphragm side, a fixed casing bottom wall portion that supports an end of the piezoelectric element on a side opposite to the diaphragm, a plunger that extends through the pressurized casing bottom-wall portion and transmits expansion and contraction of the piezoelectric element to the diaphragm, and a coil spring that is between the piezoelectric element and the pressurized casing bottom-wall portion and is supported by the first support portion to apply a compressive force to the piezoelectric element.

The invention claimed is: 
     
       1. A liquid coating apparatus comprising:
 a liquid chamber to store a liquid; 
 an inflow path that is connected to the liquid chamber to allow the liquid to be supplied into the liquid chamber; 
 a diaphragm that defines a portion of a wall portion defining the liquid chamber and is deformable to change a volume of the liquid chamber; 
 a driver expandable and contractable in at least one direction to deform the diaphragm in a thickness direction; 
 a first support portion that is between the driver and the diaphragm in the one direction to support the driver on a diaphragm side; 
 a second support portion that supports an end of the driver on an opposite side of the driver to the diaphragm in the one direction; 
 a transmission that extends in the one direction between the driver and the diaphragm and passes through the first support portion to transmit expansion and contraction of the driver to the diaphragm; and 
 a compressive force applicator between the driver and the first support portion and supported by the first support portion to apply a compressive force to the driver in the one direction. 
 
     
     
       2. The liquid coating apparatus according to  claim 1 , wherein
 the driver includes a piezoelectric element; and 
 the piezoelectric element includes multiple piezoelectric bodies laminated in the one direction. 
 
     
     
       3. The liquid coating apparatus according to  claim 1 , wherein
 the transmission has a rod shape extending along an axis; and 
 the compressive force applicator extends along an axis of the transmission between the driver and the first support portion to apply a compressive force to the driver in the one direction. 
 
     
     
       4. The liquid coating apparatus according to  claim 1 , wherein
 the compressive force applicator includes a spring extending spirally along an axis; and 
 the transmission has a rod shape and passes through the compressive force applicator in a direction of the axis. 
 
     
     
       5. The liquid coating apparatus according to  claim 1 , wherein the transmission is in a rod shape, and includes a leading end in a hemispherical shape on a driver side. 
     
     
       6. The liquid coating apparatus according to  claim 1 , further comprising:
 a protrusion in a hemispherical shape protruding in the one direction from the second support portion toward the driver and supporting the end of the driver on the opposite side of the driver. 
 
     
     
       7. The liquid coating apparatus according to  claim 1 , further comprising:
 a first base between the driver, and the transmission and the compressive force applicator. 
 
     
     
       8. The liquid coating apparatus according to  claim 6 , further comprising:
 a second base between the end of the driver on the opposite side of the driver and the protrusion. 
 
     
     
       9. The liquid coating apparatus according to  claim 1 , further comprising:
 a controller to perform drive control of the driver and to perform a repolarization process of applying a predetermined voltage to the driver for a certain period of time and then setting voltage to be applied to zero.